阅读说明：本技术 一种利用酸沉降和透析从木质素提取液中制备纳米木质素的方法 (Method for preparing nano lignin from lignin extracting solution by utilizing acid sedimentation and dialysis ) 是由 徐建 顾帅令 杨超华 吴海军 左宗涛 耿樊辉 张楷 徐霞 于 2020-12-18 设计创作，主要内容包括：本发明公开了纳米木质素制备技术领域的一种利用酸沉降和透析从木质素提取液中制备纳米木质素的方法,将氢氧化钠,生物质与1,4-丁二醇水溶液(60％,v/v)以比例为1:20:240(w/w/v)置于反应釜并充分混合均匀,在180℃下反应2h,得到反应料；将反应料进行减压抽滤,离心并收集上清,将上清缓慢滴加到去离子水中,再次离心去掉沉淀,得到木质素提取物的稀释液；利用电位滴定仪滴加盐酸调整pH后引入透析袋并使用膜过滤,得到纳米木质素分散液；本发明主要利用滴加酸降低分子表面电荷,使木质素分子聚集成纳米粒子,之后透析不仅可以提高纳米木质素均一性,而且可以直接除去溶剂中有机溶剂和氢离子,因此制备出稳定性好,分布均匀,粒径较小得纳米木质素。(The invention discloses a method for preparing nano lignin from lignin extract by utilizing acid sedimentation and dialysis, which belongs to the technical field of nano lignin preparation, sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60 percent, v/v) are placed in a reaction kettle in a ratio of 1:20:240(w/w/v) and are fully and uniformly mixed, and the reaction is carried out for 2 hours at 180 ℃ to obtain a reaction material; carrying out reduced pressure suction filtration on the reaction material, centrifuging and collecting the supernatant, slowly dripping the supernatant into deionized water, centrifuging again to remove precipitates, and obtaining a diluted solution of the lignin extract; dropwise adding hydrochloric acid by using a potentiometric titrator to adjust the pH value, introducing into a dialysis bag, and filtering by using a membrane to obtain a nano lignin dispersion liquid; the invention mainly utilizes dropwise adding acid to reduce the surface charge of molecules, so that lignin molecules are aggregated into nano particles, and then dialysis can not only improve the uniformity of nano lignin, but also directly remove organic solvent and hydrogen ions in the solvent, thereby preparing the nano lignin with good stability, uniform distribution and smaller particle size.)

1. A method for preparing nano lignin from lignin extract by using acid sedimentation and dialysis is characterized by comprising the following steps:

(1) putting sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60%, v/v) in a ratio of 1:20:240(w/w/v) into a reaction kettle, fully and uniformly mixing, and reacting for 2 hours at 180 ℃ to obtain a reaction material;

(2) carrying out reduced pressure suction filtration on the reaction materials, centrifuging and collecting the supernatant, slowly dripping the supernatant into deionized water with different amounts, keeping the rotating speed at 300rpm in the dripping process, centrifuging again to remove precipitates, and obtaining the diluents of the lignin extracts with different concentrations;

(3) and slowly dripping hydrochloric acid into the diluted solution of the lignin extract by using a potentiometric titrator to adjust the pH, then introducing into a dialysis bag, and filtering by using a membrane after dialysis to obtain the nano lignin dispersion solution.

2. The method for preparing nano lignin from lignin extract by using acid precipitation and dialysis as claimed in claim 1, wherein in step (1), the biomass is corn stalks and pine wood chips, and the biomass is dried, crushed, sieved by a 2mm sieve, washed and dried before reaction.

3. The method for preparing nano lignin from lignin extract by using acid precipitation and dialysis as claimed in claim 1, wherein in step (2), the centrifugation speed is 8000rpm, and the centrifugation time is 15 min.

4. The method for preparing nano lignin from lignin extract by using acid precipitation and dialysis as claimed in claim 1, wherein in step (2), the supernatant is added dropwise to different amounts of deionized water, and the precipitate is removed by centrifugation again to obtain diluted lignin extract solutions diluted 0, 1, 3 and 6 times.

5. The method for preparing nano lignin from lignin extract by acid precipitation and dialysis as claimed in claim 1, wherein in step (3), hydrochloric acid with concentration of 0.25M is added dropwise at stirring speed of 13rpm and 5 μ L/s by using potentiometric titrator, and pH of filtrate is slowly adjusted to 4.8-5.8.

6. The method for preparing nano lignin from lignin extract by acid precipitation and dialysis as claimed in claim 1, wherein in step (3), the dialysis bag is 8000-14000 daltons, and dialysis is carried out for three days, and water is changed twice a day.

7. The method for preparing nano lignin from lignin extract by acid precipitation and dialysis as claimed in claim 1, wherein in step (3), the pore size of the membrane is 0.45 μm.

Technical Field

The invention relates to the technical field of nano lignin preparation, in particular to a method for preparing nano lignin from a lignin extracting solution by utilizing acid sedimentation and dialysis.

Background

Lignin, the second most renewable resource of biomass after cellulose, is not completely resolved at present due to its complex composition and structure, and thus many lignins cannot be effectively utilized. The lignin can be used as a phenol substitute in the phenolic resin of the wood adhesive, but the problem of poor dispersibility of the lignin in the adhesive is serious, and in addition, the lignin is insoluble in water, so that the application effect of the lignin is not ideal. The nano lignin has higher specific surface area and higher activity. The nano lignin dispersion can effectively solve the problems.

The existing method for preparing the nano lignin still has the problems of complex process, large energy consumption, large nano lignin particles, uneven particle size distribution and the like.

Therefore, a method for preparing nano lignin from lignin extract by using acid precipitation and dialysis is proposed to solve the above problems.

Disclosure of Invention

The invention aims to provide a method for preparing nano lignin from lignin extract by utilizing acid sedimentation and dialysis, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following scheme to realize the following steps:

the invention provides a method for preparing nano lignin from lignin extract by utilizing acid sedimentation and dialysis, which specifically comprises the following steps:

(1) putting sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60%, v/v) in a ratio of 1:20:240(w/w/v) into a reaction kettle, fully and uniformly mixing, and reacting for 2 hours at 180 ℃ to obtain a reaction material;

(2) carrying out reduced pressure suction filtration on the reaction materials, centrifuging and collecting the supernatant, slowly dripping the supernatant into deionized water with different amounts, keeping the rotating speed at 300rpm in the dripping process, centrifuging again to remove precipitates, and obtaining the diluents of the lignin extracts with different concentrations;

(3) and slowly dripping hydrochloric acid into the diluted solution of the lignin extract by using a potentiometric titrator to adjust the pH, then introducing into a dialysis bag, and filtering by using a membrane after dialysis to obtain the nano lignin dispersion solution.

Preferably, in the step (1), the biomass is corn straw and pine wood chips, and the biomass is dried, crushed, sieved by a 2mm sieve, washed and dried before reaction.

Preferably, in the step (2), the centrifugal speed is 8000rpm, and the centrifugal time is 15 min.

Preferably, in the step (2), the supernatant is dripped into deionized water with different amounts, and the precipitate is centrifuged again to obtain diluted lignin extract solutions with dilution of 0 time, 1 time, 3 times and 6 times.

Preferably, in the step (3), hydrochloric acid of 0.25M concentration is added dropwise at a rate of 5. mu.L/s with a potentiometric titrator at a stirring speed of 13rpm, and the pH of the filtrate is slowly adjusted to 4.8 to 5.8.

Preferably, in step (3), the dialysis bag is 8000-.

Preferably, in step (3), the pore size of the membrane is 0.45. mu.m.

The invention has the beneficial effects that:

the method has the advantages of simple process, short time consumption and low energy consumption for dripping the dilute acid; the nano lignin has small particle size, uniform distribution and good stability; the nano lignin dispersion liquid has no organic solvent, so that the nano lignin dispersion liquid is more convenient and fast to use;

the invention discloses a method for preparing nano lignin, which mainly uses dropwise acid to reduce the surface charge of molecules, so that lignin molecules are aggregated into nano particles, and then dialysis can not only improve the uniformity of the nano lignin, but also directly remove organic solvents and hydrogen ions in solvents, thereby preparing the nano lignin with good stability, uniform distribution and smaller particle size.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A method for preparing nano lignin from lignin extract by using acid sedimentation and dialysis comprises the steps of putting sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60%, v/v) in a ratio of 1:20:240(w/w/v) into a reaction kettle, fully and uniformly mixing, and reacting at 180 ℃ for 2 hours to obtain a reaction material; carrying out vacuum filtration on the reaction materials, centrifuging at 8000rpm for 15min, collecting supernatant, slowly dripping the supernatant into deionized water, keeping the rotating speed at 300rpm in the dripping process, centrifuging at 8000rpm for 15min again, and removing precipitates to obtain diluted lignin extract diluent with the dilution of 3 times; dropwise adding 0.25M hydrochloric acid at a speed of 5 mu L/s under the condition of stirring at 13rpm by using a potentiometric titrator, slowly adjusting the pH value of the filtrate to 5.5, introducing the filtrate into a dialysis bag (8000- "14000 daltons), dialyzing for three days, changing water twice every day, and filtering by using a 0.45 mu M membrane to obtain the nano lignin dispersion.

Example 2

A method for preparing nano lignin from lignin extract by using acid sedimentation and dialysis comprises the steps of putting sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60%, v/v) in a ratio of 1:20:240(w/w/v) into a reaction kettle, fully and uniformly mixing, and reacting at 180 ℃ for 2 hours to obtain a reaction material; carrying out vacuum filtration on the reaction materials, centrifuging at 8000rpm for 15min, collecting supernatant, slowly dripping the supernatant into deionized water, keeping the rotating speed at 300rpm in the dripping process, centrifuging at 8000rpm for 15min again, and removing precipitates to obtain diluted lignin extract diluent with the dilution of 1 time; dropwise adding 0.25M hydrochloric acid at a speed of 5 mu L/s under the condition of stirring at 13rpm by using a potentiometric titrator, slowly adjusting the pH value of the filtrate to 5.2, introducing the filtrate into a dialysis bag (8000- "14000 daltons), dialyzing for three days, changing water twice every day, and filtering by using a 0.45 mu M membrane to obtain the nano lignin dispersion.

Example 3

A method for preparing nano lignin from lignin extract by using acid sedimentation and dialysis comprises the steps of putting sodium hydroxide, biomass and 1, 4-butanediol aqueous solution (60%, v/v) in a ratio of 1:20:240(w/w/v) into a reaction kettle, fully and uniformly mixing, and reacting at 180 ℃ for 2 hours to obtain a reaction material; carrying out vacuum filtration on the reaction materials, centrifuging at 8000rpm for 15min, collecting supernatant, slowly dripping the supernatant into deionized water, keeping the rotating speed at 300rpm in the dripping process, centrifuging at 8000rpm for 15min again, and removing precipitates to obtain diluted lignin extract diluent with 4 times of dilution; dropwise adding 0.25M hydrochloric acid at a speed of 5 mu L/s under the condition of stirring at 13rpm by using a potentiometric titrator, slowly adjusting the pH value of the filtrate to 5.5, introducing the filtrate into a dialysis bag (8000- "14000 daltons), dialyzing for three days, changing water twice every day, and filtering by using a 0.45 mu M membrane to obtain the nano lignin dispersion.

Result detection

1. The test method comprises the following steps: the average particle size, PDI and Zeta potential of the nano lignin were determined by analysis using a Malvern ZS 90. Specific detection results are shown in table 1.

TABLE 1 test results

Group of	Average particle diameter/nm	PDI	Zeta potential/mV
				Example 1	95.48	0.227	-30.35
Example 2	117.3	0.278	-30.89
				Example 3	91.4	0.232	-30.25

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not exhaustive. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.